Production of lubricating compositions from zirconium compounds



United States Patent 3,003,890 v PRODUCTION OF LUBRICATING COMPOSITIONS FROM ZIRCONIUM COMPOUNDS Reginald S. Dean, Hyattsville, Md., assignor to Chicago Development Corporation, Riverdale, -Md., a corporation of Delaware I No Drawing. Original application Dec. '22, 1 958, Ser. No. 781,946, now Patent No. 2,941,931, dated June 21, 1960. Divided and this application June 12, 1959, Ser. No. 820,841

4 Claims.

This invention relates to zirconium compounds. It is a division of SerialNo. 781,946, filed December 22, 1958, now Patent No. 2,941,931, granted June 21, .1960. In this application, I have disclosed the composition ZrCl and methods for production thereof. This'invention relates to the production of lubricating composition from this compound. The preferred method, of manufacture consists in electrolyzing a melt of 65% S'rCl 35% Na'Cl containing about 3% zirconium as a salt soluble in dilute HCl, using a comminuted zirconium anode contained in an annular basket surrounding an'iner t cathode such as a graphite rod. The cell is a cylindrical one of stainless steel provided'with anfiner't atmosphere and means for separating the 'cathodedeposit from the molten salt without eXp'o'sure"to air. Thefemperature isabout 1200* F. The current density o'nthe cathode is about 200- ampere s per square foot. ma am -11w replenishment by anode solution, ZrCL, is periodically added to theba'th. Analysis 'ofthe salt around the cathode *onwliiehth'e composition is formed shows an average 'valenoe ofab out 1.4 as 'determined by'reduction of ferric chloride solution anclitotal zirconium by standardme'thods. The salt around the cathode evolves new 4 n'rL/ gram 'of hydrogenwhen dissolved in ferric -chloride solution. 7

The deposit of the composition rsnnes-cn-iheeaineae is composed of large shiny flakes with only a small amount of'enclosed salt, analyzing as indicated above. Washing with dilute acid and drying provides a composition analyzing from 25-28% Cl, balance substantially zirconium. A preferred method of preparing the electrolyte is to start with an initial electrolyte containing about 6% -MnCl dissolved a melt of 6'5 SrQl' 35% -Na1 and carry out the electrolysis using a comminuted 'zirconium anode. After several runs, the cathode deposit, which is at first granular, becomes flaky and contains about 0.5% Mn. Afterseveral' more'run's', theimanganese is reduced to 0.1% or less.

It has been found that higher melting-electrolytes such as NaCl maybe used and other methods of producing the electrolyte described rnay be used.

CHEMICAL ANALYSIS OF THE COMPOSITION A spectrographic analysis ofthe'fiakes produced from commercial zirconium scrap containing 1.8% Hf and 0.2% Ti by the above described procedure was as follows:

..-Percent .01 .001

The extraordinarypurity of the product, particularly the substantial absence of Hf and Ti, is noteworthy.

CRYSTAL STRUCTURE The composition of my invention is in'th'e'form of flakes 'ofvaryin'g size. It is'particularly characterized by its crystal structure as determined "oyX raY spectrometry.

2 The following table shows the Xeray analysis of a typical sample of :the composition of .my invention compared to iodide process zirconium.

These measurements clearlyshow that my composition is characterized by planes of zirconium atoms in thealpha. iorm with only a very:slight expansion of theinterplanar spacing over zirconium made by the iodide process, :and uniquely by interplanar spacings of a different magnitude, namely nearly .four .times that .of the metallic planes. For comparison, graphite which has :a similar structure shows for 110, 1.42 A. and the distancebetween atoms in adjacent'basal planes'as 3.35, compared to 858-98 A. in the compound ormy invention. To find unit cells with planar spacing comparable to that of my invention, it is necessary to go to organiccompounds, e .g., polyvinylidene chloride has an atomic spacing of 13.69 A., 4.67 A. and 6.29 A. These structural characteristics of the composition of rny'invention characterize it as a compound and also provide a rationalization oftheproperties which I have discovered in the compound.

PRESSING PROPERTIES 4 The composition ofmy invention has in theform of flakes, a density of 4.00 as determined by pycnometerusing chloroform as the'liquid. .The composition can .be pressed in a dieat 1015'0,000.p.s.i. to form a compact with a density of 3.95 when the .flakes are randomely oriented or 3.90 when the flakes are oriented in the ,flat position in the die. By hot pressingat500 .C., the density maybe brought to 4.4 Which,.h0wever, fallsto 4.0 by stress relief at 200 .C.

Acylir'idr'ical compact pressed from random oriented vflakes'has a compressivestrength of about 40,000 p.s.i. of flatly oriented flakes of about 32,000 p.s.i. The cylinder. fails by basal slip. The. longitudinal compressionbefoyre failure is about. 10% and the lateral expansion about .1 o. 9

When compressed in a .die, the composition'remains elastic to a't'least 150,000 p.s.i. and shows a uniformelastic compression of about 0.1 in/inch. There is no substantial difierence between oriented and unoriented flakes so far as compression in adieis concerned.

The compacts of the composition of my invention have very'low tensile strength. Thisv may be greatly increased, however, by reinforcing with. metal wires or other fibres. Metal wirereinforcingis particularly effective if the wires are pre-coated with the composition by drawing through a dielubricated with the composition. This produces great adherence to the wire which can then becut into "short "lengths for reinforcing.

The elastic properties of the compositionarenot great ly afiected by temperature up to 400 C. Between 400' C. and 600 C. the composition is thermoplastic and may be extruded. The extruded material is not substantially changed in room temperature properties. Above 600 C., the composition loses its thermoplastic properties and may be heated to 1000 C. without further change. Material so heated is normally elastic up to 1000 C.

The pressing properties of the composition as above set forth make it uniquely-suitableforhightemperature packing, such as rings.

LUBRICATING PROPERTIES The composition of my invention is graphitic" in the sense that the slip of the planes over each other is much greater in one direction than in the others. This slip like that of graphite is parallel to the basal plane in this instance made up of the hexagonal alpha zirconium arrangement of atoms. The strength along the basal plane is, so far as may be determined that of metallic zirconium, the shearing strength is low due probably to the distance apart of the basal planes. This graphitic slip of the composition of my invention is the probable explanation of the lubricating properties which I have discovered in the composition of my invention.

To illustrate the lubricating properties of the compound of my invention, I have drawn titanium wire through a carbide die with a reduction from .140 in dia. to .125 dia. I have done this using no lubricant, graphite lubricant, beeswax lubricant, and the compound of my invention, and noted the pull necessary. The results follow:

Composi- No Lubrl- Graphite, Beeswax, tion of this cant, lbs. lbs. lbs. Invention,

In the case of the graphite and beeswax, the lubricant was entirely removed by the drawing process. With the compound of this invention, a tightly adherent continuous coating is left on the wire which permits further reduction through several dies without loss of lubricating properties.

The compound of my invention may be mixed with other lubricants and plastics as is done with graphite and graphitic compounds like M03 Such admixture is, however, not necessary with the compound of my invention to obtain adherence to the surface to be lubricated. Further, these admixtures lower the temperature at which the lubricant can be used. The compound of my invention retains its lubricating properties up to 1000 C.

The lubricating properties of the composition as above set forth make it useful for high temperature and high pressure lubricants and with suitable reinforcing for oil less bearings and the like.

The lubricating properties of the compound also have great advantages as a binder or addition agent in abrasive compositions. A mixture of 50% finely ground ZrCl and a fine abrasive may be pressed into forms and used for grinding metal surfaces to produce a smooth finish.

ELECTRICAL PROPERTIES The individual flakes of the composition of my inven tion are electrical conductors of highly varying magnitude. Specific resistances of the flakes as formed vary from 1-1000 ohm Cm. If a voltage of 2-3 volts is placed across a flake from surface to surface, the conductivity is decreased by jumps indicating the breakdown of some good conducting paths through the flake. In this way, the resistance is brought into a range of about 100 ohm Cm. By heating to 200 C. the resistance is increased to about 1000 ohm Cm. Flakes treated in this way are highly pressure sensitive and may be reduced to A their resistance by a pressure of grams.

Compacts of the flakes are similarly variable in resistance nad subject to the same changes on treatment as the individual flakes.

FREE ENERGY The flakes are sufliciently good conductors to form a cell when coupled in a suitable electrolyte with manganese dioxide Such a cell using 10% hydrochloric acid has a voltage of 1.85 v.

Based on a cell reaction of the free energy of the composition of my invention is 68,400 cal. This corresponds to 208,000 for ZrCl, 183,000 for ZrCl and 135,000 for ZrCl These free energies may be arbitrarily made up of 75,000+35,000 valence. Applying this arbitrary formula to the composition of my invention, it will be seen that the valence factor disappears. That is chlorine has no true valence in the composition of my invention as far as its contribution to the free energy of the composition is concerned.

REPLACEMENT REACTIONS Since the chlorine in the composition of my invention may be considered interstitial in the lattice of widely spaced zirconium layers, it may be replaced in some instances without destroying the layered lattice.

In the simplest instance, it may be replaced by hydroxyl with the evolution of hydrogen in dilute acid. Such hydrolyzed composition retain the flaky structure of the original compound and have about the same free energy as judged from their cell reactions. Hydrolysis may, however, proceed fnrther with disintegration of the structure.

The chlorine in the composition of my invention may be partially or wholly replaced in its interstitial position by organic radicals. The reactions for accomplishing this are borrowed from Organic Chemistry and are carried out in non-hydroxylated solvents such as ether or benzene. Typical reactions are the Williamson type synthesis ZrCl-+.RONa(in ether) ZrOR+NaCl The R may be any aliphatic or aromatic residue containing 2-12 carbon atoms; and the Friedel and Crafts type synthesis This compound may be leached with benzene. Homologs of benzene may be substituted for benzene.

Another synthesis of similar nature is ZrCl+ROI-I(AlCl (in benzene) ZrOR +HCl in Which the compound may be leached with benzene.

The substitution of the organic radical increases spacing of the basal zirconium planes and hence increases electrical resistance and decreases the elastic compression modulus. It is not necessary to entirely replace the chlorine to obtain these results in a considerable degree.

The substituted compositions of my invention have exceptional thermal stability and in many instances thermoplasticity at 40-600 C. They may be heated to at least 800 C. without decomposition.

The substituted or partially substituted compositions described have greater elastic deformation at lower loads and substantially improved thermoplastic properties.

What is claimed is:

1. As a composition of matter chemically homogeneous flakes of graphitic texture having the chemical formula ZrCl, with a density of about 4.0 and a single phase structure in which the interplanar spacings of the atoms include those of alpha zirconium and an additional interplanar spacing of about 8-9 A.

2. A compact article formed by compressing the commetallic filaments having been previously coated with the I composition of claim 1.

References Cited in the file of this patent UNITED STATES PATENTS Cooper et a1 May 2, 1939 Opie et a1. Sept. 15, 1959 

1. AS A COMPOSITION OF MATTER CHEMICALLY HOMOGENEOUS FLAKES OF GRAPHITIC TEXTURE HAVING THE CHEMICAL FORMULA ZRCL, WITH A DENSITY OF ABOUT 4.0 AND A SINGLE PHASE STRUCTURE IN WHICH THE INTERPLANAR SPACINGS OF THE ATOMS INCLUDE THOSE OF ALPHA ZIRCONIUM AND AN ADDITIONAL INTERPLANAR SPACING OF ABOUT 8-9 A. 